Receiving device for control information

ABSTRACT

A receiving device for control information formed by a first control signal and a second control signal transmitted after the first signal and having a duration less than the duration of the first signal, where the durations of received signals having the same frequency as the control signals are measured to generate a first output when the duration exceeds a predetermined time Ts and to generate a second output when the duration exceeds predetermined time Tc less than the time Ts. The duration of the first control signal is longer than the time Ts, and the duration of the second control signal is less than the time Ts and more than the time Tc. A controlled circuit is triggered to and selfheld in the switching-in state in response to the first output and restored in response to the second output.

1-11 ten at 3,098,212 7/1963 Creamer,.Ir...... .......i... 325/392 [72]Inventor Mnsnyulri lFulrata 941, Shimorenjalru, Mitaka-shi, Tokyo, Japan[21] AppLNo. 885,401

[22] Filed Dec. 16, 11969 Patented Dec. 11 1, 119711 g device forcontrol information signal and a second control signal signal and havinga duration less t .wmfi c m m t mm fin m C w A n Rd r m Smn Ema Arr" 8 69 1 l n. w .w ny D da. y t n o n P 1]] 23 333 [.11

than the duration of the first signal, where the durations of e samefrequency as the control nerate a first output when the duramined timeTs and to generate a duration exceeds predetermined time Ts. Theduration of the first control signal is longer than the time T5, and theduration of the h fi wn: .mt lme mwmmm 8% m m n m w mmmm d CO wk mm rlae w m 80 C mdflmT a 9 3 5 2 3 L 0 R T N 0 C, m r m E m M a v m ENW" m mGTDW NAID" H r WM m mmm om Ewes RHQJU M T U N {51] int. lilllmh 1/16second control signal is less than the time Ts and more than ed circuitis triggered to and self-held in [50] Field 325/55, the time Tc.Acontroll .228 the switching-in state in response to the first outputand restored in response to the second output.

[56] References Cited UNITED STATES PATENTS 10/1962Noller.............r............

Patented Dec. 14,, 1971 3,628,153

4 Sheets-$heet 1 4 J I I I RECEIVER AMPLIFIER Ifi L CONTROL SIGNAL J 9-7 DETECTOR I /5 AMPLIFIER TRANSMITTER CONTROL SIGNAL F151. 2 GENERATOR I-IflIIIIIIIIIflIIIIIIIIllIIIII IIIIIIIIIIIE---- e J L *7? I L -E H 7E 1:Ifi E, FL

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Patented Dec. 14, 1971 4 Sheets-Sheet 2 CONTROL SIGNAL DETECTOR 5 4SheetsSheet 4,.

w E u m l l I I I l I 1 I l l l l I I l W I l l I I l I l I I 1 I I l II I I l I I IIJ W 5:23 M i956 @2558 m3; J n w m m n 55 lm m WW m a m m mE at n n u W u m r If- ,L Q 52 55 528% w w Patented Dec. 14, 1971IRIECIEI VIING DEVICE IFDIR 'CONTIRGIL INFORMATION BACKGROUND OF THEINVENTION This invention relates to receiving devices used in a systemfor controlling, from the sending side, the receiving side in abroadcast system, such as l an emergency broadcast system fortransmitting emergency information, such as information of a naturaldisaster etc., from the broadcast station to the receivers, 2) arecorder-control broadcast system for causing recorders of thereceivers, such as tape recorders, to record the broadcast informationin accordance with the control of the broadcast station, or (3) abroadcast system for a control signal transmitted to control the switchoperation of each of various kinds of apparatus at the receiving side.

In these prior art system, a device at the receiving side isautomatically triggered by a control signal transmitted from the sendingside. However, restoration to the standby condition on the device of thereceiving side is usually performed by manual operation (hereinafterreferred as semicontrol system"). If the customer of the receiving setis absent, the receiving set of the semicontrol system remains in anunmuted condition after completion of a desired operation. This willcause unnecessary power consumption or unnecessary loud noise from thespeaker which is uncomfortable to the neighborhood. This defect tends toprevent popularization of the broadcast system of this type.

To eliminate the above difficulty, another prior art system has beenproposed in which the triggered device of the receiving side isautomatically restored by the control from the sending side (hereinafterreferred as full-control system). In this full-control system, twocontrol signals having different frequencies from each other areemployed. Two control signals A and B are simultaneously transmitted tothe receiving side. The received control signals a and b are applied toan AND gate, so that a desired control is effected at the output of theAND gate. Thereafter, one of the two control signals a and h is ceasedwhile the other is further transmitted without interruption to hold thetriggered condition of the controlled device. When the other of the twocontrol signals a and b is ceased, the controlled device is restored tothe initial condition. However, if this full-control system is appliedto an emer' gency broadcast system, coexistence of the broadcast programand one of the signals a and b is offensive to the ear. To avoid suchdiscomfort, the modulation rate of the carrier in transmitting the twocontrol signals a and b is reduced as low as possible. This causesdeterioration of the reliability of the control operation of thisfull-control system. With respect to some of receiving sets, normaltriggering and normal restoration in these receiving sets will not beperformed at all.

An object of this invention is to provide receiving devices free fromthe above defects.

The principle of this invention will be understood from the followingdetailed discussion taken in conjunction with the accompanying drawings,in which the same or equivalent parts are designated by the samereference numerals, characters. and symbols.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. I is a block diagram for illustrating an example ofconventionalreceiving devices used in the broadcast system for Control information;

FIG. 2 is a block diagram for illustrating an example of conventionalsending devices used in the broadcast system for control information;

FIG. 3 is a block diagram for illustrating the theory of operation ofthis invention;

FIG. d shows time charts explanatory of the operation of someembodiments ofa control device; and

FIG. 5 and 6 are each block diagram for illustrating an actualembodiment of one control receiving device.

To afford a better understanding of this invention, a conventionalbroadcast system for control information will first be described.

FIG. l is an example of a receiving set which comprises a receivingantenna ll, receiver 2 receiving a transmitted signal from the antenna 1and amplifying the received signal and further demodulating the receivedsignal, a control signal detector 5 for detecting a transmitted controlsignal from the received and demodulated signal, a switch 6 controlledby the output of the control signal detector 5, an amplifier 3amplifying the demodulated signal obtained at the output of the receiver2, and a speaker connected to the output of the amplifier In thisreceiving set, the switch 6 is opened in the normal case, so that thespeaker d is muted. When a control signal is transmitted from thesending side of the broadcast system, it is detected by the controlsignal detector 5, so that the switch 6 is closed and the broadcastprogram transmitted after the control signal can be heard from thespeaker 4.

FIG. 2 is an example of the sending side of the broadcast system tocontrol the receiving sets as shown in FIG. I. Broadcast program signalsare applied from a terminal I3. A control signal generator 14 generatesa predetermined control signal. The control signal generated from thecontrol signal generator M is applied to the transmitter llll. Theoutput of an amplifier l2 amplifying the broadcast programs suppliedfrom the terminal 113 is also applied to the transmitter 11. The outputof the transmitter 11 is connected to an sending antenna ll5. When aprogram is to be transmitted to the receiving sets, the control signalis at first transmitted to unmut the receiving sets and then thebroadcast program is thereafter transmitted.

With reference to FIGS. 3 and 4, the principle of this invention will bedescribed. Means l, 2, 3, 4 and 6 other than the control signal detector5 are the same as those in the receiving set shown in FIG. l. Thecontrol signal detector 5 comprises three means A, B and C in accordancewith this invention. The means A comprises a narrow band pass; filterBPF for selecting a signal of a predetermined single frequency from theoutput W, of the receiver 2 and a recifying circuit RECT for convertingthem to a DC pulse signal W,. The means B comprises a time-countingcircuit TM, and a time-counting circuit TM The time-counting circuit TM,measures the duration of the DC pulse signal W obtained from the means Aso that a first output W, is present when the duration of the DC pulsesignal W exceeds a predetermined time Ts. The time-counting circuit TMmeasures the duration of the [DC pulse signal W obtained from the meansA so that a second output W, is present when the duration of the DCpulse signal W exceeds a predetermined time To less than the time Ts.The means C is a control circuit for switching-in the switch 6 inresponse to the first output W and for switching-off the switch 6 inresponse to the second output W, generated after the termination of thefirst output W Accordingly, the switch 6 is held in the ON- state in atime from the termination of the first output W; to the start of thesecond output W The operation of the control signal detector 5 shown inFIG. 3 will be further described with reference to FIG. 4. A first markW,, of the signal W, is transmitted to switch-in the switch 6, and asecond mark W of the signal W, is transmitted to switch-off the switch6. The mark W, for switchingon the switch 6 has a duration longer than apredetermined time Ts. The mark W for switching-off the switch 6 has aduration longer than a predetermined time To but shorter than apredetermined time Ts which is longer than the time Tc. As understoodfrom FIG. 4, when the first mark W,, is transmitted, the time-countingcircuit TM generates the second output W after the time Tc from thestart of the first mark W,,. However, the control circuit is designed sothat the switch 6 is not switched-off in response to the second output WThis will be clear from actual embodiment described below.

With reference to FIG. 5, an example of the control signal detector 6 isdescribed. The above-mentioned means A, B and C are designated by dottedenclosures. The operation of this example is as follows. When the firstmark W,, is transmitted to cut offa transistor TR and the duration ofthe output W, of the means A exceeds the time Ts determined inaccordance with a product of values of a resistor R, and a capacitor C,a voltage charged in the capacitor C through the resistor R from asource +Vc is discharged through a path comprising a resistor R and atransistor Tr Accordingly, a relay RY is energized so that contacts ry,and ry are closed. In response to the close of the contact ry,, thereceiver 2 and the amplifier 3 are connected to each other. Accordingly.program information transmitted after the control signal (w can be heardfrom the speaker 4. On the other hand, the charging time constant of acapacitor Ca determined in accordance with a product of values of aresistor R and the capacitor Ca is smaller than the charging timeconstant Tc of the capacitor C. Accordingly, transistors Tr. and Tr, arerespectively turned on and off before the above-mentioned turn on of thetransistor TR This means that the hold of the relay RY is maintainedthrough the turned-on transistor TR, since the transistor TR is cut off.

However, when the first mark w is terminated, the charged voltage of thecapacitor Ca is suddenly discharged through a turned-off transistor TRso that the hold circuit of the relay RY is maintained by a path throughthe contact ry, and the transistor TR In this case, the charged voltageof the capacitor C is also discharged through a resistor R and atransistor TR However, since the discharging time constant of thecapacitor substantially determined in accordance with a product ofvalues of the capacitor C and the resistor R is larger than thedischarging time constant of the capacitor Ca determined in accordancewith a product of values of the capacitor Ca and the transistor TR thetransistor TR, becomes conductive before turnoff of the transistor TRAccordingly, the hold of the relay RY are continuously maintained. Thishold of the relay RY can be maintained by the use ofa slow-releasingrelay as the relay RY.

When the second mark w, more than the time Tc and less than the time Tsis transmitted and received, the transistor TR, becomes conductive afterthe time Tc starting from the start of the second mark w while thetransistor TR is remained in the cutoff state. Therefore, the transistorTR is turned off so that the seld-hold of the relay RY is released. Inresponse to this release of the relay RY, connection between thereceiver 2 and the amplifier 3 are cut off. This is the standbycondition for receiving a next control signal.

With reference to FIG. 6, another actural example of the control signaldetector 5 is described. ln this example, the means B comprises a singletime-counting circuit. However, the start to turn on of the transistorTR is determined so that the turn on of the transistor TR starts whenthe charged voltage of the capacitor C reaches a voltage v,, while thestart to turn on of the transistor TR is determined so that the turn onof the transistor TR, starts when the charged voltage of the capacitor Creaches a voltage v In this case, the voltage v corresponds a voltagecharged in the capacitor C in the time Ts starting from the start of thefirst mark w The voltage v corresponds to a voltage charged in thecapacitor C in the time To starting from the start of the first mark \vor the second mark W In addition to the above-mentioned analoguetechnique, digital technique or mechanical relays may be adopted to formthe means B. Moreover, the relay RY of the means C may be replaced by anelectronic circuit, such as flip-flop circuit, or by another electronicswitching circuit.

In the above examples, it is assumed that the control signal consistingof two mark signals w, and w has the same frequency. However, these twomark signals w and w may have respectively different frequencies fromeach other, in this case, the means A must be provided two combinationseach comprising the filter BPF and the recifying circuit RECT. Moreover,the means B is designed as shown in F lGS. 3 and 5.

As mentioned above, correct triggering for a controlled circuit, such asthe switch 6, an amplifier 3 and the speaker 4 shown in FIG. 3, andrestoration to the standby state for control information of the controlcircuit can be performed without spurious operation in accordance withthis invention.

if false signals similar to the control signal and included in thetransmitted broadcast program signal are eliminated by the use oftechnique proposed in my US. application for patent, Ser. No. 70l,03lfiled on Jan. 4, i968, and now US. Pat. No. 3,566,270, reliability of intransmitting the control signal will be risen further.

The above examples relate to receiving devices used in an emergencybroadcast system. However, it will be readily understood that thedevices of this invention can be applied to other control systems, suchas control of a tape recorder connected to a receiver or control of aswitch or switches of a device provided at the receiving side.

What l claim is: l. A receiving device for control information formed bya first signal and a second signal transmitted after the first signaland having a duration less than the duration of the first signal,comprising:

selection means for selecting the control information from a transmittedsignal to convert it to at least one DC signal;

time-measuring means coupled to the output of the selection means forgenerating a first output when the duration of the DC signal exceeds apredetermined time Ts and for generating a second output when theduration of the DC signal exceeds a predetermined time To less than thetime Ts, the duration of said first signal being longer than the timeTs, the duration of said second signal being longer than the time To andless than the time Ts;

first control means coupled to the output of the time-mea suring meansfor triggering a control circuit to the switching-in state thereof inresponse to the first output and for holding the switching-in state ofthe control circuit;

second control means coupled to the time-measuring means for releasingthe hold state of the first control means in response to the secondoutput; and

third control means coupled to the first and second control means forchecking the application to the first control means of the second outputuntil completion of said hold state ofthe first control means.

2. A receiving device for control information according to claim 1, inwhich the time-measuring means comprises two capacitors respectivelyhaving a charging time constant corresponding to the time Ts and acharging time constant corresponding to the time Tc.

3. A receiving device for control information according to claim 1, inwhich the time-measuring means comprises a capacitor, first detectingmeans for generating the first output when the charged voltage of thecapacitor reaches a predetermined first voltage after the time Tsstarting from the start of the first control signal, and seconddetecting means for generating the second output when the chargedvoltage of the capacitor reaches a predetermined second voltage lessthan the first voltage after the time Tc starting from the start of eachof the first and second control signals.

a: a s at

1. A receiving device for control information formed by a first signaland a second signal transmitted after the first signal and having aduration less than the duration of the first signal, comprising:selection means for selecting the control information from a transmittedsignal to convert it to at least one DC signal; time-measuring meanscoupled to the output of the selection means for generating a firstoutput when the duration of the DC signal exceeds a predetermined timeTs and for generatiNg a second output when the duration of the DC signalexceeds a predetermined time Tc less than the time Ts, the duration ofsaid first signal being longer than the time Ts, the duration of saidsecond signal being longer than the time Tc and less than the time Ts;first control means coupled to the output of the time-measuring meansfor triggering a control circuit to the switching-in state thereof inresponse to the first output and for holding the switching-in state ofthe control circuit; second control means coupled to the time-measuringmeans for releasing the hold state of the first control means inresponse to the second output; and third control means coupled to thefirst and second control means for checking the application to the firstcontrol means of the second output until completion of said hold stateof the first control means.
 2. A receiving device for controlinformation according to claim 1, in which the time-measuring meanscomprises two capacitors respectively having a charging time constantcorresponding to the time Ts and a charging time constant correspondingto the time Tc.
 3. A receiving device for control information accordingto claim 1, in which the time-measuring means comprises a capacitor,first detecting means for generating the first output when the chargedvoltage of the capacitor reaches a predetermined first voltage after thetime Ts starting from the start of the first control signal, and seconddetecting means for generating the second output when the chargedvoltage of the capacitor reaches a predetermined second voltage lessthan the first voltage after the time Tc starting from the start of eachof the first and second control signals.